Bake in centre of 325°F (160°C) oven until knife inserted in centre comes out clean, about 30 minutes. Remove cups from pan; let cool completely on rack. Refrigerate, uncovered, for 2 hours. (Make-ahead: Cover and refrigerate for up to 24 hours.)

Syrup: In saucepan, bring tea, honey, lemon juice and kumquat to boil; reduce heat and simmer until reduced to about 1/3 cup (75 mL). Let cool to room temperature. (Make-ahead: Cover and set aside for up to 24 hours.) Serve over pot de creme.